As stored program-controlled switching systems have evolved, a wide variety of useful features have been developed to extend the communication capabilities such systems provide. Incoming calling line identification, a feature that displays the caller's number for incoming calls to a called customer station, allows selective acceptance of certain calls based on the calling number while other calls are either not answered or are routed to a message center. The feature is implemented by transmitting the calling line identification to the called customer station in a data message--for example, to an analog station during a silent interval between ringing or to an integrated services digital network (ISDN) station in the out-of-band D-channel used for call control signaling. Since customers typically remember only a few, frequently called telephone numbers, a related feature that provides a display of the caller name is substantially more useful to customers in deciding whether to accept a call. With a known call waiting feature where a caller-identifying data message is transmitted out-of-band, as for an ISDN station, a customer already engaged in an ongoing telephone conversation is informed of the caller identity for a second call that is coming in. Although such features provide customers with much greater control over their telephone communications, conventional analog stations, which represent a large majority of the customer stations in use today, are not equipped to either process or display data messages. In addition, modification of the normal human response of answering a ringing telephone, such that a customer glances at a display to determine caller identity before answering, is difficult particularly for customers that use the features only infrequently.
U.S. Pat. No. 5,007,076 issued to J. R. Blakley on Apr. 9, 1991, discloses an enhanced call waiting feature implementation for use with conventional analog station sets. When a called station is busy, a call waiting signal is transmitted to the called station. If the called station flashes, a communication path between the previous caller and the called station is disconnected and the calling party name is spoken to the called station using text-to-speech. If the called party chooses to take the new call after learning the calling party name, the called station transmits a DTMF digit or allows the expiration of a predetermined time period without signaling. In response a communication path is completed between the second caller and the called station. A problem with the disclosed Blakley implementation relates to the cost and difficulty in integrating text-to-speech technology into existing switching system designs as well as providing such technology in each switching system which serves customers desiring the enhanced call waiting feature. Solution
This problem is solved and a technical advance is achieved in accordance with the principles of the invention in an exemplary call waiting deluxe method where a switching system forwards calls to a service node that provides specialized call processing, e.g., processing requiring text-to-speech, to a number of switching systems without requiring modification of the hardware design of those systems. Advantageously, only calls to busy called stations are forwarded to the service node using a call forwarding-busy line feature to avoid unnecessary delays and excessive service node traffic for normal calls. The service node uses the same directory number that was initially dialed for the call, in invoking a call waiting-originating feature which, importantly, takes precedence over the call forwarding-busy line feature and results in the transmissions of a call waiting signal to the called station. The service node obtains the calling party name from a database and responds to a flash signal from the called station by speaking the calling party name to the called party. The service node also transmits an announcement to the called station including a number of call handling options, and responds to a signal from the called station defining one of the options by controlling handling of the incoming call in accordance with the defined option. The options include transferring the incoming call to a voice message system, placing the incoming call on hold, transmitting a busy message, having the switching system continue to transmit an audible alerting signal, and accepting the incoming call.
A method in accordance with the invention is used in an arrangement comprising a switching system and a service node for specialized call processing. In response to an incoming call from a calling communication station to said switching system for a called communication station, it is determined whether the called station is busy on another call. Upon determining that the called station is busy on another call, the incoming call is forwarded to the service node. In response, the service node effects a search for information associated with the calling station. The service node causes a call waiting signal to be transmitted to the called station. Thereafter, the switching system responds to receipt of a predefined signal from the called station by disconnecting a communication path between a calling communication station for the other call and the called station. After the path is disconnected, the service node transmits speech signals, generated from the information obtained during the search, to the called station.
Illustratively, after the speech signals are transmitted and in response to receipt of a prespecified signal, e.g., a dual-tone multi-frequency (DTMF) digit or expiration of a specified time period without receiving signaling, the service node transfers the incoming call to the called station. The called station has a call forwarding-busy line feature assigned to it by the switching system and does not have a call waiting feature assigned to it by the switching system. The called station has a call waiting deluxe feature assigned to it by the service node. The call forwarding-busy line feature may be canceled on a per call basis. The service node invokes a call waiting-originating feature of the switching system, e.g., dial call waiting, and dials a directory number of the called station--the same directory number that was initially dialed for the incoming call. The call waiting-originating feature takes precedence over the call forwarding-busy line feature. At most two calls to the called station can be forwarded to the service node at the same time. The dial call waiting feature of the switching system may be invoked for only one call to the called station at a time. During the various specialized processing steps, an audible alerting signal is transmitted to the caller.